defmodule Microwaveprop.Pskr.ClientTest do
  use ExUnit.Case, async: false

  alias Microwaveprop.Pskr.Client

  setup do
    # Pre-register a placeholder under the global name so the Client
    # under test loses leader election and goes to :standby — this
    # avoids any outbound MQTT connection in the test environment.
    {:ok, placeholder} = Task.start_link(fn -> Process.sleep(:infinity) end)
    :global.unregister_name(Client)
    :yes = :global.register_name(Client, placeholder)

    on_exit(fn ->
      :global.unregister_name(Client)
      Process.exit(placeholder, :kill)
    end)

    %{placeholder: placeholder}
  end

  describe "start_link + init (standby branch)" do
    test "starts as :standby when the global name is already taken" do
      {:ok, pid} = GenServer.start_link(Client, name: __MODULE__.NotRegistered)
      state = :sys.get_state(pid)

      assert state.role == :standby
      assert state.socket == nil
      assert state.buffer == <<>>
      assert is_list(state.bands)
      assert is_binary(state.client_id)

      GenServer.stop(pid)
    end

    test "uses defaults for bands when none are passed" do
      {:ok, pid} = GenServer.start_link(Client, [])
      state = :sys.get_state(pid)

      assert "6m" in state.bands
      assert "2m" in state.bands
      assert "70cm" in state.bands

      GenServer.stop(pid)
    end

    test "honors custom bands list and aggregator name from opts" do
      {:ok, pid} = GenServer.start_link(Client, bands: ["2m"], aggregator: SomeOtherAggregator)
      state = :sys.get_state(pid)

      assert state.bands == ["2m"]
      assert state.aggregator == SomeOtherAggregator

      GenServer.stop(pid)
    end

    test "honors custom client_id" do
      {:ok, pid} = GenServer.start_link(Client, client_id: "test-client-42")
      state = :sys.get_state(pid)
      assert state.client_id == "test-client-42"
      GenServer.stop(pid)
    end
  end

  describe "tcp messages with mismatched socket" do
    test "tcp message for a stale socket is ignored", %{placeholder: _} do
      {:ok, pid} = GenServer.start_link(Client, [])
      # Send a TCP message with a fake socket that doesn't match state.socket.
      # state.socket is nil, but :tcp pattern matches when socket matches state.socket.
      # Since state.socket is nil, this falls through to the catch-all handle_info.
      send(pid, {:tcp, :stale_port, "data"})
      Process.sleep(20)
      assert Process.alive?(pid)
      GenServer.stop(pid)
    end

    test "tcp_closed for a stale socket is ignored", %{placeholder: _} do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, {:tcp_closed, :stale_port})
      Process.sleep(20)
      assert Process.alive?(pid)
      GenServer.stop(pid)
    end

    test "tcp_error for a stale socket is ignored", %{placeholder: _} do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, {:tcp_error, :stale_port, :reason})
      Process.sleep(20)
      assert Process.alive?(pid)
      GenServer.stop(pid)
    end
  end

  describe ":reconnect message routing" do
    test "schedules a connect attempt for a standby (immediate :continue, :connect)" do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, :reconnect)
      Process.sleep(50)
      # The handle_info(:reconnect) returns {:noreply, state, {:continue, :connect}}.
      # The connect will fail (no MQTT broker reachable) and schedule another retry.
      # We just verify the process didn't crash on receipt.
      assert Process.alive?(pid)
      GenServer.stop(pid)
    end
  end

  describe "terminate/2" do
    test "is graceful when state has no socket" do
      {:ok, pid} = GenServer.start_link(Client, [])
      # Just normal stop — terminate(_, %{socket: nil_or_other})
      GenServer.stop(pid)
      refute Process.alive?(pid)
    end
  end

  describe "standby handle_info" do
    test "nodeup re-runs election (stays standby while name is taken)" do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, {:nodeup, :test@nowhere})
      Process.sleep(50)

      state = :sys.get_state(pid)
      assert state.role == :standby
      GenServer.stop(pid)
    end

    test "nodedown re-runs election (stays standby while name is taken)" do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, {:nodedown, :test@nowhere})
      Process.sleep(50)

      state = :sys.get_state(pid)
      assert state.role == :standby
      GenServer.stop(pid)
    end

    test "unrelated info messages are ignored" do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, :unrelated_message)
      Process.sleep(20)

      assert Process.alive?(pid)
      GenServer.stop(pid)
    end

    test ":ping with no socket is a no-op" do
      {:ok, pid} = GenServer.start_link(Client, [])
      send(pid, :ping)
      Process.sleep(20)
      state = :sys.get_state(pid)
      assert state.socket == nil
      GenServer.stop(pid)
    end
  end
end